Enhertu (fam-trastuzumab-deruxtecan-nxki), an IV infusion, has been authorised by the U.S. Food and Drug Administration for the treatment of patients with HER2-low metastatic (spread to other areas of the body) or unresectable (unable to be removed) breast cancer. As a newly described subtype of HER2-negative breast cancer, the HER2-low subtype is the first to have a medication authorised specifically for its patients.
In the United States, 287,850 additional cases of female breast cancer are anticipated in 2022. That implies the tumours do not overexpress or create too many copies of the HER2 protein. Around 80–85 percent of those new cases were previously thought to have HER2-negative subtypes (including hormone receptor positive and triple negative breast cancer). About 60% of those diagnosed with breast cancer, who were once thought to have the HER2-negative subtype, are now thought to have the HER2-low subtype. Patients with HER2-low status previously had chemotherapy or endocrine treatment.
Treatment options for patients depend on the presence of HER2 receptors, which are proteins produced by the HER2 gene. Breast tumours that are triple negative and hormone receptor positive are classified as HER2-negative. The HER2 subtype has a new categorization called HER2-low. It defines a novel subtype of breast cancer that is not HER2-positive but does have some HER2 proteins on the cell surface.
Enhertu is approved for HER2-low breast cancer patients who have already had chemotherapy for metastatic disease or whose cancer reappeared during or within six months after finishing adjuvant therapy.